Nambu's theories, developed in 1960, have been crucial in building the standard model of particle physics, a set of theories that describe all the fundamental forces of nature, with the exception of gravity.

Japanese physicists Makoto Kobayashi, of the High Energy Accelerator Research Organization in Tsukuba, and Toshihide Maskawa, of the Yukawa Institute for Theoretical Physics in Kyoto, will split the remaining half of the prize.

The pair is being honored for explaining in 1972 how symmetry breaking works among subatomic particles known as quarks.

Their work "provides a framework for understanding why matter vastly dominates over antimatter in our universe," said physicist Curtis Callan of Princeton University, who is vice president of the American Physical Society.

Frank Close, of the University of Oxford in England, added that the deficit of antimatter is "believed to be central to why there's something rather than nothing."

Matter Annihilation

Ordinary matter has an "evil twin" known as antimatter, which is made of particles of similar mass but of the opposite electrical charge.

Negatively charged electrons, for example, have antimatter counterparts called positrons, which are positively charged particles used in medical imaging.

When matter and antimatter collide, they annihilate each other in a burst of energy.

During the big bang—the violent explosion that kick-started the universe about 14 billion years ago—matter and antimatter should have been created in equal amounts.